Use of a polyester in the preparation of coatings for the interior of can ends

Abstract

The invention relates to the use of a hydroxyl functional polyester having a glass transition temperature of at least 40 DEG C., a hydroxylnumber between 5 and 150 mg KOH/gram resin, a molecular weight (Mn) between 800 and 10.000 and a molecular weight (Mw) between 8000 and 100.000 in the preparation of coatings for the interior of can ends. The polyester has to be crosslinked with for example an amino resin or an epoxy resins.

We claim: 
     
       1. A curable can coating composition for the interior surface of a can end which comprises (i) a hydroxyl functional polyester having a glass transition temperature of at least 40° C., a hydroxyl number between 5 and 150 mg KOH/gram resin, a number-average molecular weight (Mn) between 800 and 10,000, a weight-average molecular weight (Mw) between 8,000 and 100,000 or (ii) a combination of the polyester of (i) and a crosslinker capable of crosslinking said polyester, and wherein said can end comprises a metal. 
     
     
       2. A coating composition according to claim 1, wherein the hydroxyl number is between about 50 and about 100 mg KOH/gram resin. 
     
     
       3. A coating composition according to claim 2, wherein the crosslinker is selected from the group consisting of an amino resin, an epoxy resin, a phenoxy resin, an epoxyphosphate ester, and a phenolic resin. 
     
     
       4. A coating composition according to claim 3, wherein the crosslinker is an amino resin selected from the group consisting of a benzoguanamine resin and a melamine resin. 
     
     
       5. A coating composition according to claim 3, wherein the crosslinker is an epoxy resin selected from the group consisting of bisphenol-A-epoxy compounds, hydrogenated bisphenol-A-epoxy compounds, and aliphatic epoxy compounds. 
     
     
       6. A coating composition according to claim 5, wherein the epoxy resin is a bisphenol-A-epoxy compound. 
     
     
       7. A coating composition according to claim 1, wherein the hydroxyl functional polyester has a glass transition temperature of at least 50° C. 
     
     
       8. A coating composition according to claim 1, wherein the hydroxyl functional polyester has a solids content of between about 50% and about 65%. 
     
     
       9. A coating composition according to claim 1, wherein said metal comprises at least one material selected from the group consisting of aluminum, tin plate, and steel.